In the cover plates already known, the dimensions of the front finish plate and the rear mounting plate are similar such that they can be superimposed almost perfectly.
The thickness of the cover plate is therefore that of the finish plate superimposed on the mounting plate. Since the thickness of the finish plate varies depending on the finish material used, currently, the thickness of each cover plate is different for each finish material.
Furthermore, in these cover plates, the finish plate must be made with the greatest care, firstly, to prevent the appearance of unacceptable faults such as burrs, burns or chips on the visible outer edge and, secondly, to ensure that its inner edge, which delimits each opening of the finish plate, mates perfectly with each functional part of the electrical apparatus. The cost of manufacturing these plates therefore turns out to be relatively high.